Quality control, or QC for short, is a process by which entities review the quality of all factors involved in production. This approach places an emphasis on three aspects
- Elements such as controls, job management, defined and well managed processes, performance and integrity criteria, and identification of records
- Competence, such as knowledge, skills, experience, and qualifications
- Soft elements, such as personnel, integrity, confidence, organizational culture, motivation, team spirit, and quality relationships.
Controls include product inspection, where every product is examined visually, and often using a stereo microscope for fine detail before the product is sold into the external market. Inspectors will be provided with lists and descriptions of unacceptable product defects such as cracks or surface blemishes for example. The quality of the outputs is at risk if any of these three aspects is deficient in any way.
Quality control emphasizes testing of products to uncover defects and reporting to management who make the decision to allow or deny product release, whereas quality assurance attempts to improve and stabilize production (and associated processes) to avoid, or at least minimize, issues which led to the defect(s) in the first place. For contract work, particularly work awarded by government agencies, quality control issues are among the top reasons for not renewing a contract.
Quality Control Approaches
There is a tendency for individual consultants and organizations to name their own unique approaches to quality control—a few of these have ended up in widespread use
| Terminology | Approximate year of first use | Description |
| Statistical quality control (SQC) | 1930s | The application of statistical methods (specifically control charts and acceptance sampling) to quality control. |
| Total quality control (TQC) | 1956 | Popularized by Armand V. Feigenbaum in a Harvard Business Review article and book of the same name. Stresses involvement of departments in addition to production (e.g., accounting, design, finance, human resources, marketing, purchasing, sales). |
| Statistical process control (SPC) | 1960s | The use of control charts to monitor an individual industrial process and feed back performance to the operators responsible for that process. Inspired by control systems. |
| Company-wide quality control (CWQC) | 1968 | Japanese-style total quality control |
| Total Quality Management (TQM) | 1985 | Quality movement originating in the United States Department of Defense that uses (in part) the techniques of statistical quality control to drive continuous organizational improvement. |
| Six Sigma (6σ) | 1986 | Statistical quality control applied to business strategy. Originated by Motorola. |
